The prior art is already aware of various hydraulic systems which are utilized for powering lawn mowers, and for raising and lowering the mowers under the influence of hydraulic pressure. That is, the prior art is aware of mowing machines which include a tractor unit whereon the mowers are supported for transport over the ground, and the tractor includes a prime mover and a hydraulic system for powering the mowers in the cutting action and in raising and lowering the mowers. Examples of the prior art are found in U.S. Pat. Nos. 3,511,034 and 3,563,011 and in U.S. patent application Ser. No. 506,261 filed Sept. 16, 1974, and now U.S. Pat. No. 3,918,240.
The prior arrangements of gang mowing machines, such as those cited above, normally require a complexity of a hydraulic system wherein one section of the system is utilized for controlling the rotation or powering of the grass cutter itself, and another section of the system is utilized for raising and lowering the mowers relative to the supporting tractor. That is, the prior art requires that there be two branches of a hydraulic system and that there be separate control handles and the like for each of the two branches. In that arrangement, the operator will maneuver one handle for powering the grass cutter and he will maneuver another handle for raising and lowering the mowers between their normal transport position and their ground engaging or mowing position. Accordingly, the hydraulic systems of the prior art are distinct from the one disclosed herein, and it is a general object of this invention to provide a hydraulic system wherein the arrangement is of a compact and reliable system, including the fact that the operator needs to maneuver only one handle for controlling a corresponding hydraulic motor in driving the mower and for raising and lowering that mower. In accomplishing these objctives, the present invention provides a main hydraulic valve which has a plurality of sections joined in a single valve unit, and with each section having its own handle conveniently located to the operator, for the purpose mentioned above. Still further, the present invention accomplishes the aforementioned objectives and it does so by providing a valve unit which has a total number of sections which are actually two less than the total number of mowers controlled by the sections, and this is possible in that the arrangement is such that one valve section controls three of the mowers, namely, the three center mowers in the gang of mowers.
Still another object of this invention is to provide a hydraulic system for a gang lawn mower wherein the mowers may be raised and lowered but the lowering action can take place only when the system is operating, and thus there is an element of safety and the mowers can be retained in the raised position even though the system is not active.
Another object and advantage of this invention is to provide a hydraulic system for controlling a gang of lawn mowers wherein the system includes apparatus for reversing the direction of rotation of the mowers, such that, in reel type mowers for instance, the mowers can be relieved of debris and they can be sharpened by back-lapping against their own knife bed, in the reverse rotation.